Many diseases, such as cancer, are often pernicious and very aggressive. Treatment is often complicated by the fact that some of the most effective treatment methods can have a deleterious impact on surrounding healthy tissue and cells. As a result, more recent efforts have moved toward therapies which attempt to target only unhealthy cells and thereby minimize the impact on healthy cells.
Hyperthermia is one such approach to cancer therapy. Hyperthermia associated with radiotherapy or chemotherapy is a method for cancer treatment, although the molecular mechanisms of this process are not well understood. Hyperthermia exhibits various anti-tumor effects, including damage of tumor vasculature.
Cancer cells are more sensitive to higher body temperatures than are normal cells. Hyperthermia destroys cancer cells by raising the tumor temperature to a “high fever” range, similar to the way the body uses fever naturally when combating other forms of disease. Because the body's means of dissipating heat is through cooling from blood circulation, sluggish or irregular blood flow leaves cancerous tumor cells vulnerable to destruction at elevated temperatures that are safe for surrounding healthy tissues with normal, efficient blood cooling systems.
Although not wishing to be bound by theory, scientists attribute the destruction of cancer cells at hyperthermic temperatures to damage in the plasma membrane, the cytoskeleton and the cell nucleus. Cancer cells are vulnerable to hyperthermia therapy particularly due to their high acidity caused by the inability to properly expel waste created by anaerobic metabolism. Hyperthermia attacks acidic cells, disrupting the stability of cellular proteins and killing them.
Radiofrequency (RF) hyperthermia is a non-ionizing form of radiation therapy that can substantially improve results from cancer treatment. For chemotherapy drugs that depend on blood transport for delivery, hyperthermia used in combination with chemotherapy (thermo-chemotherapy) enhances blood flow in tumor tissues, increasing the uptake of chemotherapy drugs in tumor membranes. Hyperthermia also induces disassembly of the cytoskeleton, which enlarges the tumor pores for easier drug entry. Once delivered, hyperthermic temperatures can be used as a drug activator, accelerating chemical reactions through heat and drawing essential oxygen molecules to tumor tissue for chemical reaction with the drug. This technology can be designed to optimize those factors that are antagonistic to neoplastic growth.
Several therapies are associated with non-ionizing RF hyperthermic therapy. One is RF ablation where direct radio-stimulation of cancerous tissues creates a local intense heat enough to kill neoplastic cells. Another RF approach is to direct RF at nanoparticle targets localized in the tumor site. These nanospheres are affixed with antibodies to focus the delivery of the nanoparticle to the tumor site that then becomes the target of RF stimulation to directly deliver heat to the local tissue. Still another approach is to combine the separate actions of chemotherapeutic agents with tissue hyperthermia.